I re-ran all experiments again, but with a certain noise level to the action.
The noise has been added to all dimensions of the action with a new random number.
The random number comes from a standard deviation with sigma=1 and mean=0 and has an interval of [-1;1].
A noise level of 5% means that the highest reachable noise value is equal to -5% or +5% of the possible action range.

Example:
In the SinusEnvironment the action range is equal to [0;3]. 5% of this range is 0.15 which is multiplied with a random number and than added to the action value. The action=1.0 could therefore be change to an set of values that lies in the interval [0.85; 1.15].
( actionValue = rangeLength * noiseLevel * randomNumber + realActionValue )